1. Field of the Invention
The present invention relates to a throttle valve control device for controlling air amount supplied to an internal combustion engine, and more particularly, relates to a throttle valve control device in which a throttle valve is opened/closed by a motor.
2. Description of the Conventional Art
A first example of a conventional throttle valve control device has been indicated in Japanese Patent Application Laid Open No. 2005-98178.
According to this example, an intake passage is provided through at an inner part of a throttle body, and a throttle valve is mounted on a throttle valve shaft, which crosses the intake passage and is rotatably supported to the throttle body. Accordingly, the throttle valve shaft is rotated so as to control opening/closing of the intake passage by the throttle valve.
Further, a drive gear comprising a spur gear is fixedly mounted on an end part of the throttle valve shaft.
Further, a motor is housed and provided in the throttle body, and a motor gear comprising a spur gear is mounted on an output shaft of the motor.
Further, an intermediate gear for transmitting the rotation from the motor gear to the drive gear while reducing a speed is formed in two stages with a large diameter gear comprising a spur gear and a small diameter gear comprising a spur gear, and the large diameter gear and the small diameter gear are formed along the axial direction. The motor gear is geared with the large diameter gear of the intermediate gear, and the drive gear is geared with the small diameter gear of the intermediate gear.
Accordingly, rotation of the motor is transmitted to the intermediate gear from the motor gear through the large diameter gear, and rotation of the intermediate gear is transmitted to the drive gear through the small diameter gear, and thereby, the throttle valve is opened/closed by the motor.
Further, as described above, rotation of the motor is reduced at the first stage by the motor gear and the large diameter gear of the intermediate gear, and reduced at the second stage by the small diameter gear of the intermediate gear and the drive gear.
A second example of a conventional throttle valve control device has been indicated in Japanese Patent Application Laid Open No. 2005-120897.
According to this example, rotation of the motor is transmitted to the intermediate gear from the motor gear through the large diameter gear, and rotation of the intermediate gear is transmitted to the drive gear through the small diameter gear, and the thereby, the throttle valve is opened/closed by the motor, like the above-described first example.